Construction activities have reached peak intensity on the 34-month Maxi Heap Leach Pad project for French nuclear company AREVA at its Trekkopje uranium mine in Namibia, which will feature in IM’s July issue. The Trekkopje JV, comprising Concor Roads & Earthworks as lead partner, together with Grinaker-LTA and Basil Read, reports that it has been consistently achieving its present productivity targets on what is a complicated project that requires precision planning and programme scheduling.
Upon completion the leach pad will be 4 km long and 1 km wide – the biggest of its kind in southern Africa and the second largest in the world. The sheer volume of material required is unprecedented for a project of this nature, according to Concor Project Manager Clive Meyer.
“For instance, 2,5 km of piping is being laid every day, while 3.8 Mt of material will be crushed for the overliner over a period of 17 months, with 2.5 million m2 of 2 mm HDPE (High Density Polyethylene) plastic liner being imported from the USA,” he explains. “A total of 3.7 million m3 of earth will be moved, involving the blasting of 600,000 m3 of rock. Uranium will be leached from the pad into almost 900 km of piping, with diameters varying between 100 and 700 mm.”
At the current contract peak there are more than 800 people on site, comprising the JV’s own staff and locally sourced personnel.
The cut and fill of the individual cells involves 1.8 million m3 of cut and fill. Total gypcrete usage will be 320,000 m3, with 180,000 m3 of dispersive material sourced from a borrow pit.
“The stone crushing process is slower than we envisaged at the time of tender,” Meyer comments. “We have increased the number of crushers on site to eight. The crushing rate has also been slower than we anticipated, owing to the massive volume of overliner. We need to crush at a rate of 11,000 t/d to maintain the program schedule.”
A centre corridor running down the centre of the two rows of heap leach pads has a southern turning circle which required 334,000 m3 of fill and a northern turning circle which required 265,000 m3 of fill.
Ancillary works involved a total volume of 140,000 m3 of earthworks and the construction of 14 platforms to provide a solid base on which to build the necessary foundations for the crushing and screening plants.
This is a plant-intensive project, with more than 260 items of large plant on site, including dozers, excavators, loaders, rigid frame and articulated dump trucks. The project is scheduled for completion by December 2012.
